Receiving circuits



0Q 1930- H. D. CURRIER 1,778,311

RECEIVING CIRCUITS Filed Jan. 22, 1926 ZL I I I'I I r 752/527701? 1592'5122175 zzrrien' 257 d Patented Oct. 14, 1930 HIRAM n. CURRIER, OF CHICAGO, ILLINOIS,

,ASSIGNOR 'ro YKELLOGG swITcH oABD AND SUPPLY COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS RECEIVING CIBCIJ'ITS Application filed January 22, 1926. Serial No. 82,905.

This invention relates to improvements in radio receiving circuits using radio tubes and particularly to means for controlling or altering the output volume of the circuit.

The principal object of the invention is the provision, in a receiving circult employing tubes having cathodes of comparatively large 7 mass, of simple means for controlling the volume which will cause no undesirable distortion of the sound waves received, yet, will operate to vary the volume accurately and substantially instantaneously in accordance with the adjustment of the volume controlling means.

It is believed the further disclosure of the invention will be understood most readily from a detailed description thereof taken in connection with the accompanying drawings, which schematically indicate the essential elements of a receiving circuit embodying the present invention.

Referring now to the drawings, T, T, T T and T represent five vacuum or radio tubes of the character in which the cathode is heated by a heater wire which may be electrically separate and distinct therefrom as disclosed in an application of Frederick S. McCullough Serial No. 27,679, filed May 4;, 1925. Each of these tubes T, T, etc. comprises a cathode c, a heater 7 for heating the cathode, a grid 9, and an anode or plate p.

The cathodes 0 are connected in multiple to the conductor 10 which is connected to ground at 11. The filaments f are bridged in parallel across the conductors 11 and 12 which are joined by the secondary 13 of induction coil 14, the primary coil 15 of which is in series with an appropriate source of alternating current whereby the heaters f and consequently the cathodes may be heated.

The grids g of tubes T and T are joined to the positive pole of battery C through the secondary s and s of the transformers t and t. The grid of tube T is joined through the secondary s of the transformer t to the conductor 10 and consequently to ground.

The grid of tubes t and t are joined through the secondaries s and s to the positive or non-grounded side of battery G. The plates 12 of tubes T, T, T and T are all joined to the positive pole of the whole battery B through the primaries S, S S" respectively. The plate of tube T is joined to the battery 13, intermediate its ends through the primary S In parallel with the secondary windings '8, s, s are the condensers 16, 16' and 16 respectively. The usual antenna 17 is indicated which is oined to ground at 11 through the primary S of transformer t. The receiver R may be of any desired type such as the usual loud speaker or other device.

It may be here explained that each of the cathodes employed with the tubes herein disclosed comprises a small cylindrical tube having a porcelain lining and heater therein. On account of this structure the mass of the cathode does not permit it to respond readily to the operation ofa rheostat placed in series with the heater and primary of the induction 'coil; The present invention, therefore, pro- "v1des a variable resistance 18 in parallel with the primary S of the transformer t whereby 'the volume of the output of the receiving circuit may be readily controlled without distortion of the sound waves. The resistance 18 being in parallel with the resistance of the primary S operates to vary the effective resistance between the plate and battery B and also operates to'shunt outor by-pass variable portions of the current which would otherwise pass through the primary S Thus the adjustment of the variable resistanee'or rheostat 18 operates to effectively control the volume of the sound oscillations passing to the receiver R.

The present invention provides a very simple and convenient means whereby the output volume of the circuit may be regulated and wherein the changes in volume follow instantaneously upon the adjustment of the resistance 18. Thus when the Volume adjusting knob is moved back and forth, there is no lag in the corresponding'changes in volume.

I It is to be understood that the circuit herein disclosed is of the character in which two stages of amplification of the radio frequency oscillations are provided by the tubes T and -disclosedf The invention,

' claims.

amplifier, .fier, a U-shaped heater adapted to receive al- T' and two stages of amplification of the audio frequency oscillations are provided by the tubes T and T and associated circuits, tube To? being the detector tube.

It is to be understoodthat the disclosure in the accompanying drawing is merely diagrammaticandthat thepresent invention. may be employed,

, with ny ran m nts other than the single embodiment herein be limited only-by the scope of the appended therefore,-shou1d rent supply extending from the cathode of said amplifier to the anode thereof, a winding included in said circuit, and a variable f resistance connected in the cathode anode circuit for controlling the signal repeated by the amplifier through said winding.

In testimony whereofi-I have, signed this Spec fica Having describedmy inventionfwh'atd l claim is new and desire to secure by Letters Patent of the United States isi 1. JA receiving circuit includingan audion' a vcathode for said audion ampli- -ternating current for heating said cathode to render the same active, said cathode being relatively slow to respond to changes in the heater current, an anode, for said. audion amplifier, connected between thegrid and the uni-pov -.:tential cathodeto potentialize the same, a "source of battery current-connected between agrid, asource of direct current said cathode and anode, a second audion am- ,,.the flow-of direct current fromsaid source amplifier, V a cathode between said anode and cathode to control the strength of the: signal supplied to the grid. of the second 'audion amplifier by said transformen- Y 2. Aireceivingcircuit including an audion ifier, a U-shapedresistance wirefor heating said cathode to renderthe same electronically active,

ithas a time. constant and is relatively slow a transformer connectlng said first 1 audionamphfier to said second audlon amplifier, and variable means for regulating V for said audion amplia transformer for supplying alter- V, natingcurrent, directly to the saidresistance wire, said cathode structure beingsuch that VYHIRAM D. CUBRIER- -to respond to changes of heater current, an 1 I anode for said audion amplifier,.a winding conne'ctedin a circuit between said cathode and anode, a'source of current included in 'sa1d circuit, and a variable resistance havmg one of 11's termlnals connected to said source'of current and its other terminal con- V nectedto one terminal of said winding and controlling the strengthof the oscillations adapted to berepeated, through said windingby said audion amplifier thereby conv tery trolling the volume output of the receiving =circuit.

' 3. A receivingcircuitincluding-anaudion voltage changes of heater current, a control electrode for said audion, a source of batelectrode and said cathode for potentializing the same, a source of direct current supply a; circuit including. said source of ouramplifier having an indirectly heated oath- I ode which ,is' relatively slow to respond to current connected between, said control 

